The present invention relates to locksmith tools for opening locked doors. More particularly, the present invention relates to tools for opening doors, such as those doors typically found in office buildings, having an "outer" doorknob that is locked to prevent access from the outer side of the door, and an "inner" doorknob that always turns freely to open the door from the inner side thereof.
These types of doorknob lock mechanisms are designed, among other reasons, to comply with building codes requiring that persons inside an office suite, for example, always have a quick manner of egress in case of an emergency. However, this type of lock mechanism also creates the possibility of locking individuals outside of their offices, or perhaps a particular room in their home, without a key to get back in. Several solutions to this reoccurring problem have been proposed and utilized.
Among these solutions is hiring a locksmith to pick, and/or drill the locking mechanism in the doorknob. Lock picking requires a great deal of practice, and knowledge of lock cylinders, and may take considerable time to be successful. The process may involve a manual pick, or a pick "gun." The primary problem with this method is that the improper use of a picking device can cause internal damage to the lock, thereby preventing further picking or even opening of the door with the correct key. Other difficulties include the use of specially shaped anti-pick driver pins in lock cylinders to hamper lock picking.
Another method of entry employs an electric drill to drill out the shear line, bottom pins, or top pins of the lock so that the lock's cylinder plug will turn and enable the locked door to be opened. The obvious downside of drilling the lock is that it destroys the lock cylinder and plug assembly, and could damage the other parts of the lock as well.
If the locked door is positioned underneath a false, suspended ceiling such as the type with removable tiles that extends over both sides of the door, then a locksmith or other person may gain access to the inner side of the door by climbing over it. This requires that there be no security barrier above the door, and further requires a method of ascent and a safe means of descent from above the door, typically from a height of approximately 12 feet. This method is considered unsafe for obvious reasons.
A tool has been developed by the Keydex Company for use with doors having "lever" type handles rather than the common "knob" type. The tool includes a semi-rigid arm that is inserted underneath the locked door from the outer side thereof for hooking the door lever on the inner side. The tool is pulled from the outer side of the door to draw the hooked portion of the tool downward. The downward motion of the hooked portion induces rotation of the inner door lever and thereby open the locked door. A cable attached to the hooked portion of the tool may also be pulled from the outer side of the door to assist in rotating the door lever. The problem with this type of tool is the limitation that it be used only on doors having lever type handles. The tool is unable to induce rotation of a doorknob, and therefore unable to open any door having doorknobs.
In response to the problems described above, it is an object of the present invention to provide a tool that is nondestructive, safe, and simple to operate, for opening a door having a freely turning inner doorknob from a locked outer side thereof.